**8. Interventional techniques for carotid angioplasty and stent**

Patients who are not candidates for CEA due to high surgical risk factors are defined by Medicare guidelines, and include patients with recurrent stenosis after prior ipsilateral CEA, prior radiation therapy to the neck or previous ablative neck surgery such as radical neck dissection, surgically inaccessible cervical lesion above the C2 level, presence of a CCA lesion below the clavicle, contralateral vocal cord palsy, presence of a tracheostomy stoma, or patients with a contralateral ICA occlusion. Additionally, patients who are medically unstable and high risk for surgery, with COPD or other pulmonary condition which would make removal of the endotracheal tube at the end of the surgery difficult or dangerous for the patient, or recent acute myocardial infection within 30 days would also be considered high surgical risk, and a carotid artery stent procedure could be considered.

All patients receiving angioplasty of the carotid bulb should be prepared with cardiac defibrillator pads pre-procedurally, and atropine should be readily available for immediate injection in the event of severe bradycardia or asystole. Advanced cardiac life support (ACLS) materials should be readily available in the event of a potentially fatal cardiac arrhythmia that could occur as a result of the parasympathetic reflex from carotid bulb stretch during the angioplasty. The operator can choose whether to use distal embolic protection devices, however, there is no general recommendation available from the literature to support the use of distal embolic protection devices for all cases [28–32]. The authors here will routinely use a distal embolic protection filterwire device to allow continuous perfusion while providing a barrier to capture potentially large particulate matter during stent and angioplasty for carotid atherosclerotic disease when it is safe and feasible to place such a device. Additionally, Medicare requires that all carotid stent procedures be performed with distal embolic protection devices, whenever feasible.

The patient should be pre-medicated with anti-platelet agents such as aspirin and clopidogrel, and the authors here use 325mg aspirin and 75mg clopidogrel daily for 7 days prior to a scheduled elective stent placement, or a loading dose of 325mg aspirin and 300mg clopidogrel the day prior to a semi-urgent stent placement, or the day of an emergency stent placement with supplemental abciximab given as a bolus of 0.25mg/kg up to a maximum of 20mg bolus, followed by a continuous drip of 0.125mcg/kg/min to a maximum of 10mcg/min for 24h, and then followed by 325mg aspirin and 75mg clopidogrel daily for 3 months before the next follow up angiogram. At the time of the follow up angiogram, if there is no in-stent stenosis or other reason for additional procedures, then the clopidogrel can be stopped, and the patient is continued on low-dose aspirin 81mg daily indefinitely.

stenosis with the suturing. Multiple simple interrupted sutures can also be used, but this tends to be significantly more time consuming and is no more effective than the simple running suture. The use of heparinized saline throughout the procedure and back bleeding from the ECA to flush out any loose particles just prior to placing the last 6-0 prolene suture into the carotid artery is also recommended. The clamps are then removed in the reverse order that they were placed, with the ECA clamp removed first, followed by the CCA clamp, followed lastly by the ICA clamp. There are several standard techniques to close a cervical approach incision, which would typically include a subcutaneous layer of absorbable suture placed in inverted simple interrupted fashion followed by a cosmetic skin edge reapproximation with

Patients who are not candidates for CEA due to high surgical risk factors are defined by Medicare guidelines, and include patients with recurrent stenosis after prior ipsilateral CEA, prior radiation therapy to the neck or previous ablative neck surgery such as radical neck dissection, surgically inaccessible cervical lesion above the C2 level, presence of a CCA lesion below the clavicle, contralateral vocal cord palsy, presence of a tracheostomy stoma, or patients with a contralateral ICA occlusion. Additionally, patients who are medically unstable and high risk for surgery, with COPD or other pulmonary condition which would make removal of the endotracheal tube at the end of the surgery difficult or dangerous for the patient, or recent acute myocardial infection within 30 days would also be considered high surgical risk, and a

All patients receiving angioplasty of the carotid bulb should be prepared with cardiac defibrillator pads pre-procedurally, and atropine should be readily available for immediate injection in the event of severe bradycardia or asystole. Advanced cardiac life support (ACLS) materials should be readily available in the event of a potentially fatal cardiac arrhythmia that could occur as a result of the parasympathetic reflex from carotid bulb stretch during the angioplasty. The operator can choose whether to use distal embolic protection devices, however, there is no general recommendation available from the literature to support the use of distal embolic protection devices for all cases [28–32]. The authors here will routinely use a distal embolic protection filterwire device to allow continuous perfusion while providing a barrier to capture potentially large particulate matter during stent and angioplasty for carotid atherosclerotic disease when it is safe and feasible to place such a device. Additionally, Medicare requires that all carotid stent procedures be performed with distal embolic protection

The patient should be pre-medicated with anti-platelet agents such as aspirin and clopidogrel, and the authors here use 325mg aspirin and 75mg clopidogrel daily for 7 days prior to a scheduled elective stent placement, or a loading dose of 325mg aspirin and 300mg clopidogrel the day prior to a semi-urgent stent placement, or the day of an emergency stent placement with supplemental abciximab given as a bolus of 0.25mg/kg up to a maximum of 20mg bolus,

absorbable running subcuticular sutures, sterile adhesive strips or skin glue.

**8. Interventional techniques for carotid angioplasty and stent**

carotid artery stent procedure could be considered.

214 Carotid Artery Disease - From Bench to Bedside and Beyond

devices, whenever feasible.

One potential complication with stent placement is thromboembolic events that have been found to occur in up to 10% of cases where the patient was found to not have adequate platelet inhibition with the standard anti-platelet therapy described above, and these individuals are described as "non-responders" [42]. It is now known that the incidence of non-responders to clopidogrel is potentially very high, ranging from 5-40% of treated patients, and appears to be more prevalent in the Asian population compared with the Caucasian or African populations. Clopidogrel is a pro-drug that is metabolized by the cytochrome P450 emzyme pathway in the liver into the active thiol metabolite. Factors such as platelet ADP receptor heterogeneity, poor drug absorption, drug-drug interactions, and differences in metabolism of the drug by the cytochrome P450 system, as well as patient non-compliance may all contribute to the variability of drug efficacy between individuals. Variant alleles of the CYP2C19 and CYP2C9 enzymes (CYP2C19 I331V, CYP2C9 R144C and CYP2C9 I359L) have been described to have a reduced conversion rate of the clopidogrel pro-drug into the active thiol metabolite [43]. Alternative anti-platelet agents such as prasugrel (Effient) may be used, as non-responders to clopidogrel typically will respond adequately to prasugrel. Other alternative anti-platelet agents should be evaluated with the most current pharmacological literature. A pharmacy consultation may be needed to find an effective alternative anti-platelet drug for patients who do not respond to a therapeutic level with these medications. It would be wise to test all patients who require elective pre-medication with aspirin and clopidogrel using a P2Y12 activity test before performing the procedure, whenever possible, in order to identify those patients who may be non-responders to the standard therapy.

The patient is placed in the supine position on the angiography table with the femoral artery access site prepared in the usual sterile fashion. Using the modified Seldinger technique, the femoral artery is accessed with a long access catheter typically with at least a 6F inner diameter (ID) to allow room for placement of a distal protection device and the stent device simultane‐ ously, along with any additional 0.014 or 0.018 inch microwires, termed "buddy wires," which may be placed to improve the stability of the guide catheter in the CCA. The guide catheter is positioned in the CCA just proximal to the carotid bifurcation and appropriate digital sub‐ traction angiography (DSA) is performed to optimally visualize the stenosis and the takeoff of the ICA. A 0.014 inch microwire is guided beyond the ICA stenosis using a road map. The distal protection device is deployed over the microwire into a straight segment of the ICA proximal to the petrous segment. Occasionally, the stenosis will be so severe that pre-dilation angioplasty of the stenosis with a balloon that has a low crossing profile, such as a 2.5mm x 30mm Maverick or Mini-Trek balloon, before the placement of the distal protection device or the stent may be required. Cardiovascular instability or arrhythmias are uncommon when inflating a small balloon such as this at the ICA origin. An appropriately sized stent is selected, which is typically about 30-40mm in length to cover the lesion completely and about 1-2mm greater diameter than the widest measured carotid diameter into which the stent will be deployed, typically at the bifurcation [44]. Because the carotid artery bulb is typically signifi‐ cantly larger than the cervical segment of the ICA, some carotid stents are designed with a tapered diameter, such as 6mm diameter distally and 8mm diameter proximally, to accom‐ modate for this and to prevent the stent from being significantly oversized distally for an appropriately selected diameter for the proximal ICA. The appropriately selected stent is then positioned across the ICA stenosis, taking care to avoid placement of the distal end of the stent at a curved segment of the ICA, as some patients may have a relatively tortuous ICA course. This will help to avoid kinking of the stent or occlusion or dissection of the ICA. After the stent is deployed across the lesion, a DSA run is performed to confirm the location of the stent and to evaluate for residual stenosis. An appropriately selected balloon is then chosen and positioned along the center of the greatest stenosis. At the time of balloon inflation, care should be taken to watch the heart rate and blood pressure, as stretching of the carotid bulb could result in significant bradycardia or asystole. The balloon should be inflated only a few seconds, and should not remain inflated for more than 10-20 seconds during the initial post-stent angioplasty. The balloon may be left inflated longer as long as the patient remains asympto‐ matic with the occlusion of carotid blood flow, but this should not be done for longer than 1-2 minutes at a time. The distal protection device is then recovered, taking care to avoid inad‐ vertently snagging on the stent tines and potentially dislodging the position of the stent. The femoral arteriotomy access site is then closed and the patient should remain flat with the accessed leg straight for at least 1 hour after placement of an arterial closure device, or for 4-6 hours with a sandbag or clamp to hold pressure on the femoral arteriotomy site if no closure device is used.

**Author details**

**References**

David J. Padalino and Eric M. Deshaies\*

\*Address all correspondence to: deshaiee@upstate.edu

Department of Neurosurgery, SUNY Upstate Medical University, Syracuse, New York, USA

Management of Atherosclerotic Carotid Artery Stenosis

http://dx.doi.org/10.5772/57156

217

[1] Hall HA, Bassiouny HS. Pathophysiology of Carotid Atherosclerosis. In: Nicolaides A, Beach KW, Kyriacou E, Pattichis CS, editors. Ultrasound Carotid Bifurc Atheros‐ cler [Internet]. London: Springer London; 2011 [cited 2013 May 12]. p. 27–39. Availa‐

[2] Lloyd-Jones D, Adams RJ, Brown TM, Carnethon M, Dai S, De Simone G, et al. Exec‐ utive summary: heart disease and stroke statistics--2010 update: a report from the

[3] Saver JL, Fonarow GC, Smith EE, Reeves MJ, Grau-Sepulveda MV, Pan W, et al. Time to treatment with intravenous tissue plasminogen activator and outcome from

[4] Bluth E, Carroll B, Rumack CM. The Extracranial Cerebral Vessels. Diagn Ultra‐

[5] Miller JC PhD. Imaging for Carotid Stenosis. Radiol Rounds Mass Gen Hosp [Inter‐ net]. 2012 Sep [cited 2013 May 20];10(9). Available from: http://www.mghra‐

[6] Fazel P, Johnson K. Current Role of Medical Treatment and Invasive Management in Carotid Atherosclerotic Disease. Bayl Univ Med Cent Proc. 2008 Apr;21(2):133–8.

[7] Baumgartner HR, Studer A. [Effects of vascular catheterization in normo- and hyper‐

[8] Bowen-Pope DF, Ross R, Seifert RA. Locally acting growth factors for vascular smooth muscle cells: endogenous synthesis and release from platelets. Circulation.

[9] Faggiotto A, Ross R, Harker L. Studies of hypercholesterolemia in the nonhuman pri‐ mate. I. Changes that lead to fatty streak formation. Arter Dallas Tex. 1984 Aug;4(4):

cholesteremic rabbits]. Pathol Microbiol (Basel). 1966;29(4):393–405.

ble from: http://www.springerlink.com/index/10.1007/978-1-84882-688-5\_2

American Heart Association. Circulation. 2010 Feb 23;121(7):948–54.

sound. 4th ed. Philadelphia, PA: Elsevier/Mosby; 2010.

drounds.org/index.php?src=gendocs&ref=2012\_september

1985 Oct;72(4):735–40.

323–40.

acute ischemic stroke. Jama J Am Med Assoc. 2013 Jun 19;309(23):2480–8.

## **9. Conclusions**

The NASCET evidence supports the treatment of symptomatic hemodynamically significant carotid artery stenosis of ≥50% by NASCET criteria for men, and ≥70% for women. The only trial that advocates surgical intervention for asymptomatic carotid stenosis is the ACAS trial, and surgical intervention for asymptomatic carotid artery stenosis ≥60% was supported, but other trials would support best medical management because of the very low incidence of ipsilateral stroke from asymptomatic carotid stenosis, regardless of the degree of stenosis. Carotid endarterectomy remains the gold standard treatment for patients who are medically stable enough to tolerate the surgery. Carotid angioplasty without stent placement has a high rate of recurrence of stenosis, and therefore with current devices available, patients in whom endovascular treatment has been chosen for carotid stenosis should be treated with stent placement and should be pre-medicated with anti-platelet agents such as aspirin and clopi‐ dogrel, or alternative drugs such as prasugrel in clopidogrel non-responder patients. These medications should be continued for at least 3 months post-procedurally and the low dose (81mg) aspirin should be continued indefinitely.
